The whois info paints a similar picture, but clustered in Australia – many of the companies seem to be in AU, with one in India and one in London.

If a number of them are being hosted in Houston, I'd say that there's clearly a connection here... one crappy "designer" selling "unique websites" to multiple unaware clients, possibly?

Either those companies are with a bigger/popular hosting company (IIRC The Planet was located in Houston and I guess their datacenter wasn't closed down after their acquisition) or it's a link bait.

Either way - too few information to make an educated guess.

Probably not. This town is full of hacks and thieves. (just like all the other towns I guess).

they might be just hosted in huston. Three of the sites are owned by companies located in India